Department of Chemistry, Columbia University, New York, New York 10027, United States.
J Phys Chem B. 2012 Jan 12;116(1):378-89. doi: 10.1021/jp209568n. Epub 2011 Dec 22.
Solvent plays an important role in the relative motion of nanoscopic bodies, and the study of such phenomena can help elucidate the mechanism of hydrophobic assembly, as well as the influence of solvent-mediated effects on in vivo motion in crowded cellular environments. Here we study important aspects of this problem within the framework of Brownian dynamics. We compute the free energy surface that the Brownian particles experience and their hydrodynamic interactions from molecular dynamics simulations in explicit solvent. We find that molecular scale effects dominate at short distances, thus giving rise to deviations from the predictions of continuum hydrodynamic theory. Drying phenomena, solvent layering, and fluctuations engender distinct signatures of the molecular scale. The rate of assembly in the diffusion-controlled limit is found to decrease from molecular scale hydrodynamic interactions, in opposition to the free energy driving force for hydrophobic assembly, and act to reinforce the influence of the free energy surface on the association of more hydrophilic bodies.
溶剂在纳米物体的相对运动中起着重要作用，研究此类现象有助于阐明疏水性组装的机制，以及溶剂介导效应对细胞环境中体内运动的影响。在这里，我们在布朗动力学的框架内研究了这个问题的重要方面。我们从分子动力学模拟中计算了布朗粒子所经历的自由能表面及其流体动力学相互作用。我们发现分子尺度的影响在短距离内占主导地位，从而导致与连续流体力学理论的预测有偏差。干燥现象、溶剂分层和波动产生了分子尺度的独特特征。在扩散控制极限下的组装速率发现由于分子尺度的流体动力学相互作用而降低，这与疏水性组装的自由能驱动力相反，并作用于增强自由能表面对更亲水物体的缔合的影响。
